1. Field of the Invention
The present invention relates to a protective circuit board and a battery pack using the same, and more particularly, to a protective circuit board and a battery pack using the same that includes a groove formed at one side for receiving an external connection terminal, so that an increase in thickness is prevented upon wire soldering.
2. Discussion of the Related Art
Mobile communication terminals, such as a notebook, a mobile phone, a PDA and the like, which are portable and provide various functions in addition to a communication function have been recognized as the modern necessities.
Mobile communication terminals provide the various functions, such as a communication function, a message sending/receiving function, a wireless internet function, an electronic diary function, a photographing/reproduction function and others and generally use batteries as a power source for driving.
In view of power supplying time, size and weight, a battery is recognized as being important in determining the portability and mobility of a mobile communication terminal. A battery has been developed to increase the power supplying time and to be small and light. Specifically, it is general that a battery is provided with a battery protective circuit to extend battery life and to prevent accidents.
Secondary batteries include a nickel-cadmium battery, a nickel-zinc battery, and a lithium-ion battery. Generally, the lithium-ion batteries have been widely used.
A battery is electrically connected to a protective circuit, to form a battery pack. Battery packs are largely divided into an outer battery pack and an inner battery pack, depending on the shape thereof.
FIG. 1 is an exploded perspective view of an example of a conventional inner battery pack 10. The battery pack 10 is completed by fitting top and bottom insert molding units 16 and 17 into both ends of a battery cell 15 electrically connecting a bare cell 11 and a protective circuit board 12 by spot welding or soldering, and then by wrapping the bare cell 11 in a label 18 to be finished. Instead of the top insert molding unit 16, resin molding may be performed between the bare cell 11 and the protective circuit board 12.
When a lithium ion battery is over-charged at about 4.5 V or above, since water remaining in an electrolyte inside the battery is dissolved, a hydrogen gas is generated and the pressure inside the battery increases, to generate heat and start fire.
Further, when the lithium ion battery is over-discharged at about 2.7 V or below, since lithium is over-emitted, an active substance of an electrode melts by reacting with an electrolyte.
Therefore, the protective circuit board for the battery prevents the battery from being over-charged at about 4.35 V or above, converts the battery to a charge state when a voltage drops at about 4.0 V or below, and prevents the battery from being over-discharged at about 2.3 V or below.
Further, when the lithium ion battery has load or an over-current is generated due to an abnormality of a power set of a mobile communication terminal, the protective circuit board for the battery performs a function of shutting off power.
FIG. 2 is a plan view of an example of a protective circuit board 20 included in a battery pack. The protective circuit board 20 comprises a board 21, a control unit 22 mounted on the board 21, a switch unit 23, resistors 24 and 25, a capacitor 26, positive and negative battery connection terminals B+ and B−, and positive and negative power terminals P+ and P−.
The control unit 22 senses over-charge, over-discharge or over-current and turns on/off the switch unit 23 to apply/shut off the power of a circuit.
The resistors 24 and 25 and the capacitor 26 protects an IC chip used as the control unit 22 and the switch unit 23 from an abnormal voltage or static electricity and remove a noise generated in a power source unit of the IC chip.
The positive and negative battery connection terminals B+ and B− are electrically connected to the bare cell, and the positive and negative power terminals P+ and P− are connected to the mobile communication terminal and form an electrical path upon charging and discharging.
Then, when wire soldering is performed to the positive and negative power terminals P+ and P−, the positive and negative power terminals P+ and P− thicken by the thickness of the wire or soldering part. Moreover, since no part for supporting the wire is formed, the position of the wire is movable upon the soldering and therefore it is difficult to perform the work.
Moreover, when the terminals to be soldered are positioned closely to one another, there is a problem in that a risk of a short is high.